Basic aluminum halides (also referred to as aluminum halohydrates) have long been known to possess antiperspirant activity . These antiperspirant compositions are available in the form of polymeric compositions having the empirical formula: EQU Al.sub.2 (OH).sub.6-y X.sub.y
wherein X is chlorine, bromine or iodine and y has a numerical value from about 0.7 to about 3. However, it is only in recent studies, as described in U.S. Pat. No. 4,359,456 (the '456 patent), that it has been shown by size exclusion chromatography that basic aluminum halides are composed of individual polymer bands which pertain to different molecular weight groups of the compound. In these studies of basic aluminum halides obtained by conventional methods of preparation it was shown that it can further be broken down from high molecular weight polymers into larger amounts of lower molecular weight polymers by diluting concentrated aqueous solutions thereof to lower aqueous concentrations and treating with heat and or aging at room temperature to produce more effective antiperspirants as shown in sweat reduction panel studies.
The '456 patent describes processes for the preparation of improved antiperspirant compositions of aluminum halohydrates, which involve heating a 2.5 to 8.5% by weight, based on aluminum, of an aqueous solution of an aluminum halohydrate of the formula: EQU Al.sub.2 (OH.sub.6-y)X.sub.y
where X and y are as defined above, at a temperature of 50.degree. C. to 140.degree. C. for a period of time to impart to the aluminum product certain desired properties in respect of size exclusion chromatogram test bands. The products thus obtained from these processes have good antiperspirant activity, but the processes do not provide compositions containing larger amounts of the lower molecular weight polymers with a narrow polydispersity which are believed to possess greater antiperspirant activity.
In addition to the '456 patent, processes for the preparation of antiperspirant basic aluminum halides are shown in U.S. Pat. Nos. 3,507,896, 3,891,745, 3,904,741, 4,038,373 and 4,053,570. However, none of these patents disclose polymeric compositions possessing the desired amounts of the lower molecular weight polymers as measured by the size exclusion chromatogram test band.
U.S. Pat. Nos. 5,358,694 and 5,356,609 of Giovanniello disclose a method for preparing enhanced polymeric basic aluminum halides having the empirical formula: EQU Al.sub.2 (OH).sub.6-y X.sub.y.nH.sub.2 O
wherein y has a numerical value from about 0.7 to about 3; X is chlorine, bromine or iodine; n is a numeral from about 0.8 to about 4.0 and the polymer distribution as characterized by size exclusion chromatogram test is:
(a) 100% of the aluminum containing polymers are found in bands II, III and IV, and (b) band III contains at least 25% of the polymers can be prepared by reacting an aluminum metal with a halogen compound having the formula AlX.sub.3.H.sub.2 O or HX were X is as previously defined, while maintaining the temperature of the reaction mixture at about 50.degree. C. to about 100.degree. C. The aluminum metal is preferably in the form of pellets or powder.
The amount of water used is such as to have the final concentration of the polymer solution, in percent by weight, in the range of about 8% to about 35%, preferably about 8% to about 25%, more preferably about 15% to about 25%, and most preferably from about 17% to about 22% by weight. The reaction temperatures are preferably in the range of about 95.degree. C. to about 100.degree. C. Antiperspirant actives thus formed are referred to herein as "enhanced basic aluminum halides" and "enhanced basic aluminum chlorides". A fully basic form is referred to as "aluminum chlorohydrate".
Complexes of zirconium hydroxychloride and aluminum chlorhydrate are known in the art as having antiperspirant activity as disclosed in Great Britain Patent No. 2,144,992, published Mar. 20, 1985, entitled "ANTIPERSPIRANTS". The product is prepared by heating a 2-20% solution to at least 50.degree. C. until a ratio of the heights of peaks 4 to 3 as measured by gel permeation chromatography exceeds 2:1. Complexes of the aluminum/zirconium compound with amino acids are also known in the art. While these compounds contain lower molecular weight polymers to increase efficacy they also have a wide polydispersity, a higher polymer form of aluminum to zirconium glycinate complexes and a lower cationic charge. This is evidenced from higher molecular weight polymers found in peaks (1+2) as shown in the U.K. Patent No. 2,144,992 referred to above.
U.S. Pat. Nos. 4,775,528, 5,114,705 and 5,486,347, all of which are based on the same disclosure disclose a method for preparing an enhanced Al/Zr/glycinate complex by a process which is a modification of the process disclosed in U.S. Pat. No. 4,359,456 discussed above.
Improved Al/Zr/glycinate complexes and the process for making them are disclosed in U.S. Pat. No. 4,871,525 of Giovanniello and Howe, assigned to Westwood Chemical Corporation. These compounds are prepared by first preparing a basic aluminum chloride having the empirical formula: EQU Al.sub.2 (OH).sub.6-y X.sub.y.H.sub.2 O
wherein y, X and n are as defined above.
The basic aluminum halide so formed is subsequently reacted with zirconium hydroxychloride and a neutral amino acid such as glycine. The aluminum chlorhydrate/zirconium hydroxyhalide complex of the '525 patent is characterized in that the peak height ratio of peak 4 to peak 3 is about 0.05 to about 1.8:1 and the peaks (1+2) content of the complex is less than 4% of the metal containing polymer distribution by weight.
The prior art, including U.S. Pat. Nos. 4,775,528, 5,114,705, 5,486,347, and 4,871,525 all disclose that solutions of the Al/Zr/glycinate complex are unstable if maintained in solution form. The method of manufacture disclosed requires rapid drying of the solution to the powder. In the alternative, the solution must be utilized without cooling while still fresh.
It is advantageous to be able to ship solutions of antiperspirant actives for direct use in aqueous based antiperspirant formulas. Avoidance of the drying step results in significant economies in production. Furthermore, where the customer for such solution intends to utilize the antiperspirant active in solution, it is preferable not to handle the dry powder and redissolve it, but work with the solution initially. Furthermore, although the Al/Zr/glycinate complexes are more effective than antiperspirant actives that do not contain zirconium, the zirconium compounds utilized are the more expensive component. Where more efficacious forms of Al/Zr glycinate complexes are available such as with the invention product, reducing the quantity of zirconium compound is economically advantageous while at the same time maintaining the efficacious properties of the active.
Throughout this disclosure chromatographic peak profiles are sometimes referred to as "bands." The relationship of "band" to "peak" is as follows: band I=peak 1+2; band II=peak 3; band III=peak 4; band IV=peak 5; etc.